Control systems have been previously advanced for regulating the flow of water or other liquids. In U.S. Pat. No. 4,420,811 to Tarnay et al., issued Dec. 13, 1983, and entitled "Water Temperature and Flow Rate Selection Display and Control System and Method," a computer-controlled water temperature and flow rate system is disclosed. This system is characterized by the use of two proportional valves. One valve is used to receive hot water while the second valve is used to receive cold water. The valve openings can be incrementally adjusted using stepper motors. A single mixing valve used in a temperature control system is disclosed in U.S. Pat. No. 4,322,031 issued to Gehlert on Mar. 30, 1982, and entitled "Control for Sanitary Mixing Valve." A sensor detects the temperature of the water outputted from the mixing valve and a programmed microprocessor is used in controlling the temperature of the water outputted by the mixing valve. A mixing unit for a temperature-volume controlled system is described in U.S. Pat. No. 3,721,386 issued Mar. 20, 1973, to Brick et al. and entitled "Temperature-Volume Controlled Mixing Valve." A desired temperature of water is compared with the actual temperature of the water to produce a control signal for controlling the operation of a motor connected to the mixing unit. None of these liquid or water systems utilizes a binary arrangement of on/off valves for controlling the temperature of water.
In systems for controlling the flow of one or more gases, it is known to arrange a number of on/off valves in a parallel manner. In U.S. Pat. No. 3,905,394 to Jerde issued Sept. 16, 1975, and entitled "Flow Control System," a system for controlling the flow of gas, not liquid, is disclosed. Gas from a source at a predetermined pressure and temperature is supplied to a number of valves. Each of the valves communicates with an orifice, with each of the orifices being of a different size and having a predetermined binary relationship relative to the other orifices. For proper operation, the flow rate of both the inputted and the outputted gas is equal to or greater than the sonic rate. The flow rate of the output gas is monitored by a controller, which is used in controlling the opening of the valves. There is no monitoring and controlling of the temperature of the output gas. Another gas system that is used to control the flow rate of gas to a demand line is shown in U.S. Pat. No. 3,437,098 issued Apr. 8, 1969, to Stark et al. and entitled "System of Automatic Controls for Gas Mixing." This gas system also utilizes on/off valves, but in controlling the opening of the valves, a switch arm can only be moved in one step increments. Consequently, it may be necessary to step through a number of valve positions before the desired states of the on/off valves are reached. An apparatus for regulating the ratio of mixing of two gas flows while maintaining a constant overall flow rate is described in U.S. Pat. No. 3,886,971 issued June 3, 1975, to Lundsgaard et al. and entitled "Apparatus for Regulating the Ratio of Mixing of Two Fluid Flows." In this apparatus, a number of on/off valves are provided with flow resistors connected thereto which are used to vary the volume of fluid flow therethrough. Input of gas to the valves is under the control of a computer or an A/D converter. There is no monitoring of the output flow of gas. The valves are arranged in a parallel manner while the flow resistors are arranged according to a binary pattern whereby the volume of gas through one flow resistor has a binary relationship to the volume of gas through the remaining flow resistors. The flow resistors are pieces of tubing of identical inside diameter, and each has a predetermined length to achieve a binary relationship among the gas flow rates through the tubing pieces.
In addition to water temperature control systems and gas flow rate control systems, there are numerable other control systems such as disclosed in U.S. Pat. No. 4,384,462 issued Mar. 24, 1983, to Overman et al. and entitled "Multiple Compressor Refrigeration System and Controller Thereof." However, such known systems are not directed to efficiently and effectively controlling the temperature of water using on/off valves arranged according to a binary pattern and do not utilize the features of the present invention.
As can be appreciated from the foregoing prior art, there are many known systems that monitor and/or control the temperature of a liquid. There are also prior art gas systems that utilize on/off valves arranged in a binary pattern to control the flow rate of one or more gases. However, each such system fails to fully satisfy all of the objectives sought in a water temperature control system. Known systems for controlling temperature of water have utilized two proportional-type valves or a single mixing valve. The use of proportional valves significantly adds to the expense of the system and increases the response time associated with reaching a desired water temperature. Further expense ensues when it is necessary to replace the proportional valves because of wear. The use of on/off valves in the present invention reduces the expense associated with the water temperature control system and decreases the response time. Additionally, none of the known binary-related systems has been able to achieve the compact configuration of the present invention which results in reduced manufacturing cost, reduced response time and minimal space occupied by the system when it is held in position and attached to hot water and cold water pipes located in a house or other building.